this isn't working

-assumenosideeffects class mypackage.Log {
    public static void v(...);
    public static void d(...);
    public static void i(...);
}

and can't apparently get kotlin syntax working

You have instance methods in the interface, try removing the

static

keyword from the proguard rules

doesn't seem to work. It does nothing

proguard works at bytecode level, so nothing kotlin related here. probably it's not working because Log is an interface, not a class. try to assumenosideeffects

interface

rather than class. also, remove

static

as said above.